Liquid image formation apparatus and liquid developing device

Abstract

An excess toner removal area is made broader over the whole area with respect to a developer applied area that is broader than an image effective area. Thereby a liquid developer, that tends to spread slightly broader than the applied area after being applied to a photoreceptor drum, is removed by a sweep roller that can sweep excess toner present in an area broader than the original applied area and an excess toner remaining area is then prevented from being formed on the photoreceptor drum. Accordingly, the excess toner on the latent image carrier is removed as much as possible, and a transfer medium and peripheral members are prevented from being soiled due to residual excess toner.

1. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 a cleaning unit which cleans said sweep roller, wherein 
 an elastic constant of a material for said cleaning unit is within a range from 100 MPa to 5000 MPa. 
 
 
   
   
     2. The liquid developing device according to  claim 1 , wherein said nip forming unit forms a nip by a pressure control unit configured to control a pressure of said sweep roller against said latent image carrier. 
   
   
     3. The liquid developing device according to  claim 2 , wherein said pressure control unit has a mechanism configured to adjust said pressure. 
   
   
     4. The liquid developing device according to  claim 1 , wherein said sweep voltage applying unit is formed of a conductive biasing member, and said conductive biasing member comes into contact with said sweep roller to apply said sweep voltage thereto. 
   
   
     5. The liquid developing device according to  claim 4 , wherein said sweep voltage applying unit has a conductive wearing member provided on a contact surface with said sweep roller so that a contact part between said sweep roller and said sweep voltage applying unit always wears. 
   
   
     6. The liquid developing device according to  claim 4 , wherein said sweep voltage applying unit is configured to apply said sweep voltage to said sweep roller by coming into contact with a core metal of said sweep roller. 
   
   
     7. The liquid developing device according to  claim 1 , wherein said contact/separation unit is so constructed that said sweep roller is separated from said latent image carrier by a displacing device and said sweep roller is brought into contact with said latent image carrier by a pressure control unit. 
   
   
     8. The liquid developing device according to  claim 7 , wherein said contact/separation unit is so constructed that said displacing device has a cam and said sweep roller separates from said latent image carrier through rotation of said cam. 
   
   
     9. The liquid developing device according to  claim 1 , wherein said sweep roller is formed in a multilayer structure including a core metal and at least one surface layer as said elastic body. 
   
   
     10. The liquid developing device according to  claim 9 , wherein said elastic body has a volume resistivity of 10 9  ohms-cm or below. 
   
   
     11. The liquid developing device according to  claim 9 , wherein said elastic body has a hardness of 50 degrees (JIS-A) or below. 
   
   
     12. The liquid developing device according to  claim 9 , wherein said elastic body does not swell due to the carrier liquid, nor is impregnated with said carrier liquid. 
   
   
     13. The liquid developing device according to  claim 9 , wherein the at least one surface layer is a film layer having a thickness of 100 μm or below. 
   
   
     14. The liquid developing device according to  claim 9 , wherein said at least one surface layer is a film layer having a volume resistivity of 10 9  ohms-cm or below. 
   
   
     15. The liquid developing device according to  claim 1 , wherein a surface moving speed of said developer carrier is substantially the same as a surface moving speed of said latent image carrier. 
   
   
     16. The liquid developing device according to  claim 1 , wherein said cleaning unit is a cleaning blade having a contact position with respect to said sweep roller that is a central position or lower in the vertical direction. 
   
   
     17. The liquid developing device according to  claim 16 , wherein an angle of said cleaning blade is formed in a minus direction with respect to a vertical direction, and a moving member is disposed in the vicinity of said cleaning blade. 
   
   
     18. The liquid developing device according to  claim 1 , wherein said cleaning unit is a rubber member having a JISA hardness within a range from 50 degrees to 80 degrees. 
   
   
     19. The liquid developing device according to  claim 1 , wherein said cleaning unit has a blade formed of an elastic body, that has a JISA hardness within a range from 50 degrees to 80 degrees, bonded to a thin plate as a rigidity imparting member. 
   
   
     20. The liquid developing device according to  claim 1 , wherein said cleaning unit is subjected to an oil-repellent treatment. 
   
   
     21. The liquid developing device according to  claim 1 , wherein cylindrical members each having a smaller outer diameter than the outer diameter of said sweep roller are provided in both ends of said sweep roller, and the nip width, formed when said sweep roller is brought into contact with said latent image carrier, is adjusted to an appropriate one. 
   
   
     22. The liquid developing device according to  claim 1 , wherein said sweep roller is formed in a multilayer structure including a core metal and an elastic layer with at least one layer as the elastic body. 
   
   
     23. The liquid developing device according to  claim 1 , wherein said sweep roller has a volume resistivity of 10 9  ohms-cm or below. 
   
   
     24. The liquid developing device according to  claim 1 , wherein said elastic body has a hardness of 50 degrees (JIS-A) or below. 
   
   
     25. The liquid developing device according to  claim 1 , wherein said elastic body does not swell by said carrier liquid, nor is impregnated with said carrier liquid. 
   
   
     26. The liquid developing device according to  claim 1 , wherein the surface of said sweep roller has a surface roughness value of 3 μm or below. 
   
   
     27. The liquid developing device according to  claim 1 , wherein said elastic body is formed of urethane base resin as its main component. 
   
   
     28. The liquid developing device according to  claim 1 , wherein a surface of said sweep roller is a film layer having a thickness of 100 μm or below. 
   
   
     29. The liquid developing device according to  claim 1 , wherein a surface of said sweep roller is a film layer having a volume resistivity of 10 9  ohms-cm or below. 
   
   
     30. The liquid developing device according to  claim 1 , wherein said elastic body is a foam. 
   
   
     31. The liquid developing device according to  claim 1 , wherein a surface moving speed of said sweep roller is substantially the same as a surface moving speed of said latent image carrier. 
   
   
     32. The liquid developing device according to  claim 1 , further comprising a cleaning unit which cleans the surface of said developer carrier. 
   
   
     33. The liquid developing device according to  claim 1 , wherein said developer carrier is a belt-like carrier. 
   
   
     34. The liquid developing device according to  claim 33 , wherein said developer carrier has a hardness of 60 degrees (JIS-A) or below. 
   
   
     35. The liquid developing device according to  claim 1 , wherein said developer carrier is a roller-like carrier. 
   
   
     36. The liquid developing device according to  claim 35 , wherein said developer carrier has a hardness of 40 degrees (JIS-A) or below. 
   
   
     37. The liquid developing device according to  claim 35 , wherein an electrical resistivity between the surface of said roller-like developer carrier and a roller shaft of said developer carrier is 10 9  ohms or below. 
   
   
     38. A liquid image formation apparatus comprising:
 a latent image carrier; 
 a latent image forming unit which forms a latent image on said latent image carrier; 
 a liquid developing device according to  claim 1 ; and 
 a transfer unit which transfers the visualized image on said latent image carrier to a transfer material. 
 
   
   
     39. The liquid developing device according to  claim 1 , wherein said developer carrier is formed of urethane base resin so as to have conductivity. 
   
   
     40. The liquid developing device according to  claim 39 , wherein said developer carrier is a belt-like carrier. 
   
   
     41. The liquid developing device according to  claim 40 , wherein said developer carrier has a hardness of 60 degrees (JIS-A) or below. 
   
   
     42. The liquid developing device according to  claim 39 , wherein said developer carrier is a roller-like carrier. 
   
   
     43. The liquid developing device according to  claim 42 , wherein said developer carrier has a hardness of 40 degrees (JIS-A) or below. 
   
   
     44. The liquid developing device according to  claim 42 , wherein an electrical resistivity between the surface of said roller-like developer carrier and a roller shaft of said developer carrier is 10 9  ohms or below. 
   
   
     45. The liquid developing device according to  claim 39 , wherein the surface of said developer carrier has a surface roughness value of 3 μm or below. 
   
   
     46. The liquid developing device according to  claim 39 , wherein a conductive surface layer is provided on said developer carrier. 
   
   
     47. The liquid developing device according to  claim 39 , wherein the surface of said latent image carrier is formed of amorphous silicon. 
   
   
     48. The liquid developing device according to  claim 39 , wherein a surface moving speed of said developer carrier is substantially the same as a surface moving speed of said latent image carrier. 
   
   
     49. The liquid developing device according to  claim 39 , wherein a surface moving speed of said sweep roller is substantially the same as a surface moving speed of said latent image carrier. 
   
   
     50. The liquid developing device according to  claim 39 , further comprising a cleaning unit which cleans the surface of said developer carrier. 
   
   
     51. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, wherein 
 said rotation driving unit has a latent image carrier end gear disposed in the end part of said latent image carrier; and 
 a sweep roller end gear disposed in the end part of said sweep roller so as to be engaged with said latent image carrier end gear, and 
 said sweep roller end gear drives to rotate said sweep roller. 
 
   
   
     52. The liquid developing device according to  claim 51 , wherein said rotation driving unit drives to rotate said sweep roller so that a surface moving speed of said sweep roller is substantially the same as a surface moving speed of said latent image carrier. 
   
   
     53. The liquid developing device according to  claim 51 , wherein said rotation driving unit has a one way clutch disposed in said sweep roller end gear. 
   
   
     54. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, said liquid developing device further comprising: 
 a development voltage applying unit configured to apply a development voltage to said developer carrier, said development voltage producing a development electric field between an image portion of said latent image carrier and said developer carrier, and said development electric field having a direction that moves toner to said image portion, wherein 
 said sweep voltage produces a sweep electric field having a direction that attracts stray excess toner present between a background of said latent image carrier and said sweep roller to said sweep roller, and said sweep electric field not being strong enough to peel said toner adhering to said image portion. 
 
   
   
     55. A liquid image formation apparatus including the liquid developing device according to  claim 1 , said liquid image formation apparatus further comprising:
 a latent image forming unit which forms a latent image on said latent image carrier; and 
 a transfer unit which transfers the visualized image on said latent image carrier to a transfer material. 
 
   
   
     56. The liquid image formation apparatus according to  claim 55 , wherein said sweep roller is separated from said latent image carrier when the liquid developing device or liquid image formation apparatus is not in use. 
   
   
     57. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, wherein 
 said cleaning unit is a cleaning blade having a contact position with respect to said sweep roller that is a central position or lower in the vertical direction, and 
 said cleaning blade is disposed so that said cleaning blade is in contact with said sweep roller at a position having an angle θ formed with a horizontal surface of said sweep roller, and said cleaning blade is in contact with said sweep roller at an angle α formed between a tangential direction at a contact point of said blade with said sweep roller and said blade, and the angle θ is made greater than the angle α. 
 
   
   
     58. A liquid developing device according comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, wherein 
 said cleaning unit is a cleaning blade having a contact position with respect to said sweep roller that is a central position or lower in the vertical direction, said liquid image formation apparatus further comprising: 
 a conveying unit, which moves toner after being removed in an axial direction, disposed close to said cleaning blade. 
 
   
   
     59. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, wherein 
 said cleaning unit is a cleaning blade having a contact position with respect to said sweep roller that is a central position or lower in the vertical direction, and 
 said cleaning blade and an associated holding part are electrically floated from the main body of said liquid developing device, and a bias is applied to said cleaning blade so that the potential is substantially the same as that of said developer carrier. 
 
   
   
     60. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, wherein 
 said cleaning unit is a cleaning blade having a contact position with respect to said sweep roller that is a central position or lower in the vertical direction, and 
 said cleaning blade and an associated holding part are electrically floated from the main body of said device when the material of said cleaning blade has an electrical resistivity of 10 12  ohms or above, and this part is grounded. 
 
   
   
     61. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, wherein said elastic body is formed with silicone base resin as its main component. 
 
   
   
     62. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, said liquid developing device further comprising: 
 a development voltage applying unit configured to apply a development voltage to said developer carrier, said development voltage producing a development electric field having a direction that moves liquid developer to said latent image carrier when a latent image on said latent image carrier is developed with said liquid developer carried on said developer carrier, wherein 
 said sweep voltage produces a sweep electric field having a direction that attracts excess liquid developer or toner to said sweep roller in order to remove said excess liquid developer or toner adhering to or floating around the surface of said latent image carrier or its periphery after development, and said sweep electric field not being strong enough to peel said toner adhering to the developed latent image on said latent image carrier. 
 
   
   
     63. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, wherein 
 said toner contains pigment, and a thickness of a liquid developer to be applied to said developer carrier is set so that a pigment content in said toner carried on the surface of said developer carrier per square cm is within a range from 0.1 μg to 2 μg. 
 
   
   
     64. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 a cleaning unit which cleans said sweep roller, wherein 
 said developer carrier is formed of urethane base resin so as to have conductivity, said liquid developing device further comprising: 
 a development voltage applying unit configured to apply a development voltage to said developer carrier, said development voltage producing an electric field having a direction that moves said liquid developer to said latent image carrier when a latent image on said latent image carrier is developed with said liquid developer carried on said developer carrier, wherein 
 said sweep voltage produces a sweep electric field having a direction that attracts excess liquid developer or toner to said sweep roller in order to remove said excess liquid developer or toner adhering to or floating around the surface of said latent image carrier or its periphery after development, and said sweep electric field not being strong enough to peel said toner adhering the developed latent image on said latent image carrier. 
 
   
   
     65. A liquid developing device comprising:
 at least one developer carrier which carries a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein; and 
 an applying member which applies said liquid developer to said developer carrier, said liquid developing device for developing a latent image formed on a latent image carrier by said liquid developer carried on said developer carrier, further comprising:
 at least one sweep roller formed of an elastic body for removing excess developer on said latent image carrier after development, located downstream said developer carrier in a direction in which the surface of said latent image carrier moves; 
 a nip forming unit which forms a nip between said sweep roller and said latent image carrier; 
 a sweep voltage applying unit which applies a sweep voltage to said sweep roller; 
 a rotation driving unit which drives to rotate said sweep roller; 
 a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 
 a cleaning unit which cleans said sweep roller, wherein 
 said developer carrier is formed of urethane base resin so as to have conductivity, said liquid developing device, and 
 said toner contains pigment, and a thickness of a liquid developer to be applied to said developer carrier is set so that a pigment content in said toner carried on the surface of said developer carrier per square cm is within a range from 0.1 μg to 2 μg. 
 
   
   
     66. A method, comprising:
 providing and moving a latent image carrier; 
 forming a latent image on the latent image carrier; 
 providing at least one developer carrier; 
 applying a highly viscous and highly concentrated liquid developer consisting of a carrier liquid and toner dispersed therein to said developer carrier; 
 applying the developer from the developer carrier to the latent image carrier to develop the latent image on the latent image carrier; 
 providing at least one sweep roller formed of an elastic body, the sweep roller being located downstream of said developer carrier in a direction in which a surface of said latent image carrier moves; 
 forming a nip between said sweep roller and said latent image carrier; 
 applying a sweep voltage to said sweep roller; 
 rotating said sweep roller and removing excess developer on said latent image carrier; with the sweep roller after development of the latent image on the latent image carrier 
 providing a contact/separation unit which brings said sweep roller into contact with and separates said roller from said latent image carrier; and 
 cleaning said sweep roller with a cleaning unit having a cleaning material with an elastic constant within a range from 100 MPa to 5000 MPa.